1. Field of the Invention
The present invention relates to a heating body.
2. Description of the Related Art
Generally, a heating body is a device for converting electric energy into heat energy A conventional heating body includes a filament that is a heating element, a quartz tube in which the filament is inserted, and a connection unit for connecting the filament to an external power source.
That is, the filament formed of a carbon material is inserted in the quartz tube and the quartz tube is sealed. The filament is connected to the external power source by the connection unit. The quartz tube is filled with inert gas such as vacuum gas or halogen gas so as to prevent the filament from be oxidized when the filament emits high temperature heat and thus increase the service life of the heating body.
Meanwhile, the carbon filament is formed in a spiral shape, a plate shape, a linear shape, or the like. The carbon filament may be connected an electrode by a clip or a spring providing a tension. Therefore, the filament is disposed in the quartz tube without contacting an inner surface of the quartz tube. The quartz tube is molten or broken at a temperature above 800° C. Therefore, when the carbon filament emitting heat contacts the inner surface of the quartz tube, the quartz tube may be damaged and thus the service life of the heating body is reduced. Therefore, the carbon filament is supported in the quartz tube by the clip or spring without directly contacting the inner surface of the quartz tube.
That is, in the conventional heat body, the carbon filament is tensioned by outer force not to contact the inner surface of the quartz tube. However, when the carbon filament emits high temperature heat, the carbon filament expands according to its thermal expansion coefficient. When the carbon filament expands, it may physically contact the inner surface of the quartz tube, thereby damaging the quartz tube and reducing the service life of the heating body.